A population of over 10,000 diabetic patients receiving their primary care from over 450 collaborating physicians (representing over 98 percent of physicians in this category) in an eleven county area were identified. During the first year of the study, charts were reviewed and information such as age of onset and duration of diabetes, current age, medication status level of glucose control, and blood pressure status was recorded. In the second and third years of the study all juvenile onset insulin dependent diabetic patients (Type I) and a sample of adult onset (Type II) diabetic patients will be examined. The examination will consist of a questionnaire, a complete eye examination with vision determined by ETDRS protocol, stereo fundus photographs, height, weight, and blood pressure determination using HDFP protocol, and urine analysis with C-peptide determination. The prevalence and severity of diabetic retinopathy will then be determined and the association between the onset, progression and severity of retinopathy and diabetes type, duration, blood pressure level, smoking history and other factors will be determined.